The processes of hydroformylation and carbonylation are well known in the art and involve reactions represented by: ##STR1## wherein the aldehydes and alcohols produced generally correspond to the compounds obtained by the addition of a carbonyl or carbinol group to an olefinically unsaturated carbon atom in the starting material with simultaneous saturation of the olefin bond. Isomerization of the olefin bond may take place to varying degrees under certain conditions with consequent variation in the products obtained.
The hydroformylation reaction does not generally proceed in the absence of catalysts, and a disadvantage of many of the hydroformylation processes disclosed heretofore is their dependence upon the use of soluble cobalt or rhodium-containing catalysts, particularly the commonly-used cobalt-derived homogenous `oxo` catalysts, which generally necessitate the use of exceedingly high pressures to remain stable under the conditions employed.
The production of aliphatic aldehyde and alcohol hydroformylation products having a relatively high normal to branched product isomer ratio and more than four carbon atoms per molecule is often difficult in many of the practical scale processes now in use. Another problem in many commonly practiced hydroformylation processes is by-product formation resulting from competing reactions. Examples of such unwanted by-products include alkanes, formed through competing olefin hydrogenation, olefin isomers formed through double bond isomerization, ketone formation and aldols generated as a result of product aldehyde condensation reactions.
In commercially practiced hydroformylation processes cobalt- and rhodium-catalyzed systems are most commonly used,.sup.1 and while cobalt and rhodium have been the focus of much of the prior hydroformylation research, numerous other metals have been disclosed as catalysts for this synthesis. FNT .sup.1 (For a review of the prior art pertaining to the use of cobalt and rhodium-based hydroformylation processes see: R. L. Pruett, "Advances in Organometallic Chemistry", Vol. 17, p. 1 (1979) ).
Typical of the prior art relating to the use of ruthenium as a hydroformylation catalyst are the publications of Wilkinson and co-workers. In British Pat. No. 1,138,601, Example 6, the hydroformylation of alpha-olefins (1-hexene) to aldehydes is described using soluble, phosphine-stabilized ruthenium catalyst precursors, such as [(Ph.sub.2 EtP).sub.6 Ru.sub.2 Cl.sub.2 ]Cl. Here moderately high pressures are used and the use of a two step hydroformylation and subsequent hydrogenation step as a synthetic route to alcohols is discussed. Additional information regarding the use of a variety of tertiary-phosphine-ruthenium complexes in the catalytic hydroformylation of alkenes to aldehydes, particularly the dependence of conversion and aldehyde ratios upon catalyst concentration, temperature, partial and total pressures, nature of the substrate, and the addition of excess phosphine, may be found in a second publication by this group in J. Chem. Soc. p. 399 (1976). Similar classes of catalysts are disclosed also in U.S. Pat. No. 3,239,566, assigned to Shell Oil Company. In particular, this patent relates to the production of aldehydes and/or alcohols by the addition of carbon monoxide and hydrogen to olefinic hydrocarbons in the presence of a catalyst consisting of a ruthenium or rhodium component in complex combination with carbon monoxide and a trialkylphosphine. Here, the greatest percentage of the converted olefins form alcohols and aldehydes with less than seven carbons.
The use of ruthenium salts, such as ruthenium(III) chloride and ruthenium stearate, as well as ruthenium carbonyls and ruthenium-on-carbon, as catalyst precursors for the hydroformylation of olefins to straight-chain and branched aldehydes is disclosed in British Pat. Nos. 966,461 and 999,461, assigned to Imperial Industries Limited. Pettit, in U.S. Pat. No. 4,306,084, describes an oxo process reaction where the ruthenium carbonyl catalyst is maintained in a basic solution. Recently the cluster anion, [HRu.sub.3 (CO).sub.11 ].sup.-, has been shown to catalyze the hydroformylation of ethylene and propylene to C.sub.3 -C.sub.4 aldehydes in dimethylformamide at 100.degree. C. (See C. Suss-Fink, J. Organomet Chem., 193, C20 (1980)).
Polymer-bound ruthenium hydroformylation catalysts, prepared, for example, by reacting diphenylphosphinated styrenedivinylbenzene resins with ruthenium-phosphine complexes, have also been described recently. Pittman, in J. Org. Chem. 46, 1901 1981, finds improved normal/branched aldehyde ratios with these resins compared with homogeneous catalyst versions. Formation of these polymeric catalysts results from displacement of monomeric ligands from ruthenium complexes by polymeric ligands.
U.S. Pat. No. 3,239,569 discloses the production of aldehydes and alcohols in a single stage conversion which comprises contacting an olefinic hydrocarbon with carbon monoxide and hydrogen in the presence of a catalyst system comprising cobalt in complex combination with carbon monoxide and a trialkylphosphine. Here the majority of the hydroformylation products were six carbons or less.
U.S. Pat. No. 3,847,997 discloses a hydroformylation catalyst comprising a solid polymer of a tri-valent phosphorus-containing compound having associated therewith a metal from the group consisting of cobalt, rhodium, ruthenium, platinum and palladium. In the Examples recorded, the greatest weight ratio of linear aldehydes was 67 and in most examples the figure was much lower.
U.S. Pat. No. 4,045,493 describes a process for production of aldehydes and alcohols wherein a hetergeneous catalyst is employed which consists of polyphenylene comprising benzene ring structurally bonded into a polymer chain. Here, catalyst separation and recovery problems are reduced, but the percentage of straight chain products is only about 38%.
The hydroformylation catalysts discussed in U.S. Pat. No. 4,179,403 comprise an ion exchange resin, an organic linking compound ionically bound to said resin and a metal complexible moiety. The preparation of these polymeric catalysts requires the use of compounds which have both basic (or acidic) sites and transition metal ligating sites; such compounds are relatively difficult to prepare and expensive.
In another example of the use of hydroformylation catalysts comprising a metal center bonded to a polymeric ligand, U.S. Pat. No. 4,198,353 teaches of a recoverable and reusable hydroformylation catalyst having the general structure P-MCl.sub.3 wherein P is a heterocyclic nitrogen-containing polymer and M is rhodium or iridium. This system overcomes the rhodium recovery problem by chemically bonding the rhodium and iridium to an insoluble polymeric pyridine support allowing recovery from the reaction mixture by direct filtration. While this invention represents an advance in catalyst recovery, there is still not a consistent high rate of conversion to straight chain aldehydes.
In U.S. Pat. No. 4,328,125 is disclosed the use of polymeric quaternary ammonium salts to prepare ionically supported transition metal catalysts. Such ammonium salts are less thermally stable than phosphonium salts, and these catalysts were prepared from relatively expensive metal complexes.
The object of this invention is to devise a ruthenium-containing hydroformylation catalyst that also contains a polymeric, phosphonium-containing counterion component, which is active for the selective oxonation of olefin substrates to their corresponding aldehydes and alcohols, and which furthermore leaves no metal in solution, thus allowing easy separation of liquid products from the insoluble polymeric catalyst. Additionally an object is to produce predominantly linear aldehydes. A further object is to devise a system which shows reasonable activity at low pressures.
It should be noted that in previously disclosed polymeric hydroformylation catalysts polymeric electronically neutral ligands have generally been used as supports; in these the metal center is coordinated to the support through dative bonding (FIG. 1A). With the catalyst of this invention a polymeric phosphonium cation serves as support, which results in the formation of a transition metal complex ionically bonded to the support. (FIG. 1B). Furthermore, the use of this invention of readily available ruthenium-containing catalyst precursors such as ruthenium (IV) oxide instead of more expensive complexes is advantageous. ##STR2##